benet: stricter vxlan offloading check in be_features_check

When VXLAN offloading is enabled, be_features_check() tries to check if
an encapsulated packet is indeed a VXLAN packet. The check is not strict
enough, and considers any UDP-encapsulated ethernet frame with a 8-byte
tunnel header as being VXLAN. Unfortunately, both GENEVE and VXLAN-GPE
have a 8-byte header, so they get through this check.

Force the UDP destination port to be the one that has been offloaded to
hardware.

Without this, GENEVE-encapsulated packets can end up having an incorrect
checksum when both a GENEVE and a VXLAN (offloaded) tunnel are
configured.

This is similar to commit a547224dceed ("mlx4e: Do not attempt to
offload VXLAN ports that are unrecognized").

Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/emulex/benet/be_main.c

@@ -5155,7 +5155,9 @@ static netdev_features_t be_features_check(struct sk_buff *skb,
 	    skb->inner_protocol_type != ENCAP_TYPE_ETHER ||
 	    skb->inner_protocol != htons(ETH_P_TEB) ||
 	    skb_inner_mac_header(skb) - skb_transport_header(skb) !=
-	    sizeof(struct udphdr) + sizeof(struct vxlanhdr))
+		sizeof(struct udphdr) + sizeof(struct vxlanhdr) ||
+	    !adapter->vxlan_port ||
+	    udp_hdr(skb)->dest != adapter->vxlan_port)
 		return features & ~(NETIF_F_CSUM_MASK | NETIF_F_GSO_MASK);
 
 	return features;